W-Band CMOS Down-Conversion Mixer Using CMOS-Inverter -Based RF GM Stage for Gain and Linearity Enhancement

Abstract

We demonstrate a W-band down-conversion mixer with CMOS-inverter-based RF transconductance (GM) stage in 90 nm CMOS. Due to the current bleeding and GM contribution of the upper PMOS transistors of the RF GM stage, a larger load resistance can be adopted and a larger GM can be obtained while keeps the same linearity. This leads to a conversion gain (CG) enhancement. In addition, the second-order term GM (${g}_{2}$) and third-order term GM (${g}_{3}$) of the main NMOS transistors of the RF GM stage can be cancelled by those of the upper PMOS transistors and the auxiliary NMOS transistors of the RF GM stage. This leads to a better linearity. The mixer consumes 4 mW and achieves CG of 13.9-17.5 dB and LO-RF isolation of 40. 6-43.5dB for frequencies of 70-100GHz. Furthermore, the mixer achieves prominent noise figure (NF) of 16.4 dB and output third-order intercept point (OIP3) of 14.1 dBm at 94 GHz. These results demonstrate that the proposed down-conversion mixer is very promising for 94 GHz image radar sensors.